Laminated article containing resinous impregnation composition



LAMINATED ARTICLE CONTAINING RESINOUS lMPREGNATlON CUMPOSITIGN Norman E.Martello, Turtle Creek, Pa., assignor to Westinghouse ElectricCorporation, East Pittsburgh, Pa., a corporation of Pennsylvania NoDrawing. Application April 13, 1953, Serial No. 348,598

12 Claims. (Cl. 154-43 This application is a continuation-in-part ofapplication, Serial No. 320,343, filed November 13, 1952.

This invention relates, generally, to an emulsified resin varnish forproducing bearings, molded plates, tubes, abrasive Wheels and the like.

It has been proposed, heretofore, to introduce certain lubricating andWear resistant mineral compounds into selected resinous compositionswhen the composition is to be used for forming bearings, molded plates,tubes, abrasion wheels or the like. The purpose of adding the mineralcompounds is to decrease the coeflicient of friction and/or prolong thelife of the article produced.

It is customary in producing compositions for such articles as listedabove, to prepare an emulsion with the resin and mineral compound whilethe resin is in the A- stage. A continuous sheet of paper or fabric isthen impregnated with the emulsified resin, after which the resin isadvanced by heat treatment to the B-stage.

A resinous bearing or laminated article is generally made by stacking ina mold a number of strips, cut from a B-stage resin impregnated sheet,and then curing the resin to the final infusible C-stage by heat andpressure, thereby consolidating the strips into a laminated unit.

Difiiculty has arisen in producing such molded articles in obtaining asatisfactory dispersion of the mineral compounds in the resinouscompositions due to flocculation and uneven scattering thereof, and alsoin obtaining a high bond strength in the molded units preparedtherefrom.

Further, there was the disadvantage in preparing the emulsified resinsof the necessity to heat to temperatures of approximately 100 C. withconstant stirring. The resulting suspensions had the furtherdisadvantage of being inherently of high viscosity. Even with theextensive preparations of heating and stirring, the suspensions hadlittle stability, thus necessitating their immediate use.

An object of this invention is to provide an improved resinous bearingmaterial having embodied therein, by means of a novel combinedsuspending-dispersing agent, a solid lubricant for lowering thecoelficient of friction and a wear resistant mineral compound to prolongthe life of the bearing.

A further object of this invention is to provide a stable emulsifiedresin suitable for producing improved laminated articles, the resinhaving embodied therein one or more mineral compounds by means of anovel combined suspending-dispersing agent comprising a mixture of asuspending agent selected from at least one of the group consisting ofcarboXy methyl cellulose, methyl cellulose, casein, sodium alginate, andgum tragacanth, and a dispersing agent comprising a lignin sulphonate.

A further object of this invention is to provide a resinous laminatedmaterial of high bond strength, the resin having uniformly dispersedtherein mineral compounds for modifying the properties thereof.

A further object of this invention is to provide a method of makingresinous laminated material comprising the steps of impregnating afabric sheet with an emulsified United States Patent may be varied asdesired.

Patented Nov. 29, 1955 ice resin-varnish having uniformly suspendedtherein a mineral compound, and then covering the impregnated sheet witha coating of substantially only phenolic resin.

Other objects of the invention will in part be obvious and Will in partappear hereinafter.

I have discovered that certain solid lubricants, wear resistant mineralcompounds and abrasive mineral compounds can be successfullyincorporated in phenolic resinous varnish compositions by means of anovel combined suspending-dispersing agent, thereby enabling thepreparation of improved molded articles. The lubricating compounds foundto give the best results are-graphite, and the sulphides, selenides andtellurides of tungsten, molyb denum, and titanium. The mineral compoundsfound to give the best wear resistant and/or abrasive properties havebeen found to be aluminum oxide and silicon carbide. Mysuspending-dispersing agent is used to incorporate these mineralcompounds in a water or alcohol soluble thermosettable phenolic resin,and will provide a stable emulsified phenolic resin varnish, theviscosity of which Important advantages of my varnish are that littlestirring and no heating are required in its preparation and that themineral compounds will remain suspended in the stabilized varnish overlong periods of time.

In the formulation of the emulsified phenolic resin varnish inaccordance with my invention, a water or alcohol soluble thermosettablephenol-formaldehyde, cresolformaldehyde or a cresylic acid-formaldehyderesin in the A-stage is used. The term phenolic as used herein isintended to embrace all of the above type resins. In the production ofthe type of phenolic base resins referred to, from 0.8 to 2 moles of 40%aqueous formaldehyde, para-formaldehyde or other polymers thereof andother aldehydes, as Well known to those skilled in the art, are reactedWith one mole of a phenol. A water soluble phenolic resin suitable forthis application is described in the patent to Weltman et al. No.2,579,637, issued December 25, 1951.

In the compositions of this invention there are em-- bodied one or morelubricating mineral compounds or wear resisting mineral compounds, orcombinations of both, to provide an article having desired propertiessuitable for the type of service for which the article is designed. Theamount of a mineral compound that may be suspended individually in theemulsified resin varnish of my invention is as follows, based on theweight of the emulsified resin varnish: 5% to 30% of aluminum oxide, 10%to 60% of silicon carbide, 3% to 20% graphite, or 2% to 20% of thesulphides, selenides, and tellurides of tungsten, molybdenum andtitanium. The minerals are employed in a finely divided state,preferably passing through a sieve having 200 or more meshes to thelineal inch.

As the suspending agent for the mineral-compound, I employ from 0.5% to3% by weight, based on the Weight of the emulsified resin varnish of atleast one material selected from the group consisting of carboxy methylcellulose, methyl cellulose, casein, sodium alignate, and gumtragacanth.

To prevent flocculation of the mineral compound and suspending agent, adispersing agent in the amount of from 0.1% to 3% by weight, based onthe weight of the emulsified resin varnish, of sodium or calcium ligninsulphonate or both is used. In order to insure solubilizing of thedispersion agent, a small, but effective amount, in the order of 0.1% ofan alkali, such as sodium hydroxide or potassium hydroxide, is added.

When a water solvent phenolic resin is used, from 5% to 20% by weight,based on the weight of the emulsified resin varnish, of a simple alcoholsuch as methyl, ethyl,

or propyl alcohol may be admixed with the resin varnish to act as astabilizing agent therefor.

The components of the phenolic resin varnish formulation, except themineral compound, are admixed and stirred thoroughly in a mixer for afew minutes and the composition is then ready for the addition of thefinely divided mineral compound. The mineral compound is added to thephenolic resin varnish and stirred for a few minutes until the mineralcompound is suspended therein. It is then ready for use as an impregnantfor fibrous materials such as a fabric or paper to be later molded intolaminated or other fibrous reinforced bearings. Examples of othersuitable fibrous materials are cotton duck, cambric and the like. Thebase fabric or paper may be impregnated with the phenolic resin varnishin any conventional manner, for example, as described in the patent toWeltman et al. No. 2,579,637.

The base fabric or paper is initially impregnated with an amount,sufiicient to provide a resin ratio of from 1.4 to 2.0, of theemulsified phenolic resin with the solid lubricant suspended therein andthen advanced to the B-stage. In order that the finished bearing willhave a higher bond strength, the initially impregnated sheet may befurther impregnated with a conventional varnish composed substantiallyonly of phenolic resin, that contains no solid lubricant. Theconventional phenolic varnish, is added to the previously impregnatedfabric in an amount sufficient to provide a B-stage sheet having a resinratio of from 1.8 to 2.5.

Resin ratio is defined as the ratio of the weight of the untreatedfabric sheet plus the weight of the resin that is impregnated in thesheet, to the weight of the untreated sheet.

The B-stage sheets are cut to size and molded in a hot press atpressures of from 500 to 2000 p. s. i. or higher and at temperatures offrom about 140 C. to 160 C. It is to be understood, that if desired, theB- stage sheets may be run through a chopper, and the macerated materialmolded into an article.

The following is an example of the preparation of an emulsified resinvarnish in accordance with my invention.

Example I To 3.9 parts by weight of water was added 0.1 part by weightof sodium hydroxide, and 0.3 part by weight of calcium ligninsulphonate. The mixture was stirred until the ingredients weredissolved. To a separate quantity of 11.7 parts by weight of water wasadded 4 parts by weight of carboxy methyl cellulose, and this wasstirred until the carboxy methyl cellulose was dissolved. Then Whilestirring 80 parts by weight of a water solution of an A-stagephenol-formaldehyde resin of the type described in the patent to Weltmanet al. No. 2,579,637, containing 75% by weight of the resin, thepreviously prepared solutions of sodium hydroxide-calcium ligninsulphonate and the carboxy methyl cellulose were added, with stirringbeing continued for fifteen minutes thereafter. The emulsified phenolicresin composition was then ready for addition of a mineral compound.There was then added 6.6 parts by weight of 325 mesh molybdenumdisulphite to the composition with rapid stirring. In a few minutes aneven suspension was produced.

The molybdenum disulphide may be added immediately to the phenoliccomposition and the suspension stored until ready for use or themolybdenum disulphide may be added later when desired, i. e. up to atime immediately preceding the impregnation of a fabric or paper withthe phenolic resin-molybdenum disulphide suspension.

The composition was of such low viscosity that it was employed toimpregnate 50 ounce woven cotton belting. The belting Was wellimpregnated to provide B-stage phenolic resin and lubricant to a 1.5ratio, and the molybdenum disulphide coated the cotton fibers evenly.The belting was further impregnated with a varnish comprisingsubstantially only the phenolic resin used in the making of thesuspension, and advanced to the B-stage to provide the belting with atotal resin ratio of 1.9. A plurality of plies of the impregnatedbelting were superimposed and molded in a hot press to produce a Wellbonded laminated bearing. The uniformly distributed molybdenumdisulphide in the phenolic resin of the bearings provided foroutstanding low coefficient of friction in use.

Example 11 An emulsified resin varnish was prepared in the same manneras described in Example I, except that an alcohol soluble cresylicacid-formaldehyde base resin with isopropyl alcohol as a solvent wasused.

Example III The following resinous impregnating composition was preparedby adding 0.67 part by weight of carboxymethyl cellulose to 14.8 partsby weight of water and stirring until the carboxymethyl cellulose wasdissolved. To this solution there was added 0.34 part by weight ofcalcium lignin sulphonate and 0.16 part by weight of sodium hydroxide.To the resulting emulsion there was added 48 parts by weight of analcohol soluble cresylic acidformaldehyde base resin, and 16 parts byweight of isopropyl alcohol, the mixture being stirred for 15 minutes.To this emulsified resin varnish there was then added 325 mesh aluminumoxide and the mixture stirred until the aluminum oxide was completelydispersed. The resinous impregnating composition was then ready for use.

Example IV An emulsified resin varnish composition was prepared in thesame manner as described in Example III, except that no alcohol was usedto stabilize the solution, and graphite was used as a lubricant. Thefollowing ingredients were used in preparing the formulation: 16.5 partsby weight of graphite, 62.4 parts by weight cresylic acid-formaldehydebase resin, 19.4 parts by weight tap water, 0.9 part by weight ofcarboxymethyl cellulose, 0.5 part by weight calcium lignin sulphonate,and 0.3 part by weight of sodium hydroxide.

Example V An emulsified resin impregnating composition was prepared inthe same manner as described in Example 111, except that silicon carbidewas used as a wear resisting mineral compound instead of aluminum oxide.The following ingredients were used in the formulation of thecomposition: 56.4 parts by weight of silicon carbide, 30.1 parts byweight of a cresylic acid-formaldehyde base resin, 3.8 parts by weightof isopropyl alcohol, 0.4 part by weight carboxymethyl cellulose, 0.2part by weight of calcium lignin sulphonate, and 0.1 part by weight ofsodium hydroxide.

The preparation of the emulsified resin varnishes of my invention isgreatly simplified over those known in the prior art as no heat andlittle stirring is required. After its preparation, it may besatisfactorily stored for considerable periods of time before use,either with or without the mineral compound suspended therein. Theemulsified varnishes heretofore known do not hold the mineral compoundsin suspension for any appreciable time.

The mineral compounds are dispersed throughout the resin with aremarkable degree of uniformity. The uniformly distributed mineralcompounds facilitate making molded articles having outstandingcoeflicients of friction and/ or wear resistant properties in use,together with abrasive qualties in selected applications.

Since certain obvious changes may be made in the above procedure anddifferent embodiments of the invention could be made without departingfrom the scope thereof, it is intended that all matter contained in theabove description shall be interpreted as illustrative and not in alimiting sense.

I claim as my invention: 1. A resinous impregnating compositioncomprising an A-stage emulsified phenolic resin comprising thepotentially thermosettable reaction product of a phenol selected fromthe group consisting of phenol, cresol, and cresylic acid and analdehyde selected from the group consisting of formaldehyde andparaformaldehyde, having admixed therewith from 0.5% to 3% by weight ofa suspending agent selected from the group consisting of carboxy methylcellulose, methyl cellulose, casein, sodium alginate, and gumtragacanth, from 0.1% to 3% by Weight of a dispersing agent selectedfrom the group consisting of sodium and calcium lignin sulphonate, andsubstantially 0.2% by weight of an alkali to solubilize the dispersingagent, the emulsified resin having suspended there at least one mineralcompound selected from the group consisting of aluminum oxide, andsilicon carbide in an amount by Weight, based on the weight of theemulsified resin, as follows: 5% to 30% of aluminum oxide, and to 60% ofsilicon carbide.

2. The resinous impregnating composition of claim 1 in Which there isadmixed from 5% to 25% by Weight, based on the weight of the emulsifiedresin of an alcohol selected from the group consisting of methyl, ethyl,and propyl, the alcohol acting as a stabilizing agent for the resinemulsion.

3. A laminated material comprising, in combination, a fibrous basematerial, at least one mineral compound for modifying the properties ofthe material, a small but effective amount of a suspending agent for themineral compound selected from the group consisting of carboxy methylcellulose, methyl cellulose, casein, sodium alginate and gum tragacanth,a small but effective amount of a dispersing agent of a ligninsulphonate, a small but effective amount of an alkali to solubilize thedispersing agent, and a phenolic resin comprising the potentiallythermosettable reaction product of a phenol selected from the groupconsisting of phenol, cresol, and cresylic acid and an aldehyde selectedfrom the group consisting of formaldehyde and paraformaldehyde, theWhole consolidated under heat and pressure.

4. A laminated material comprising, in combination, a fibrous basematerial, at least one mineral compound for modifying the properties ofthe material, a small but eifective amount of a suspending agent for themineral compound selected from the group consisting of carboxy methylcellulose, methyl cellulose, casein, sodium alginate and gum tragacanth,a small but eifective amount of a dispersing agent of a ligninsulphonate, a small but effective amount of an alkali to solubilize thedispersing agent, and a phenolic resin derived from the reaction productof a phenol selected from the group consisting of phenol, cresol, andcresylic acid, and an aldehyde selected from the group consisting offormaldehyde and paraformaldehyde, the Whole consolidated under heat andpressure.

5. A laminated material comprising, in combination, a fibrous basematerial impregnated with an emulsified phenolic resin varnish, whichupon being subjected to heat and pressure will form a cured infusibleWhole, the phenolic resin being derived from the reaction product of aphenol selected from the group consisting of phenol, cresol, andcresylic acid, and an aldehyde selected from the group consisting offormaldehyde and paraformaldehyde, there being suspended in theemulsified resin, at least one mineral compound and from 0.5 to 3% byweight, based on the weight of the emulsified resin, of a suspendingagent for the mineral compound selected from the group consisting ofcarboxy methyl cellulose, methyl cellulose, casein, sodium alginate, andgum tragacanth, from 0.1% to 3% by Weight, based on the weight of theemulsified resin, of a dispersing agent selected from the groupconsisting of sodium and calcium lignin sulphonate,

6 and substantially 0.2% by weight, based on the weight of theemulsified resin, of an alkali to solubilize the dispersing agent.

6. In a laminated article, a plurality of resin impregnated sheetsbonded together by heat and pressure as a whole, the sheets beinginitially impregnated with an emulsified phenolic resin varnish, theresin being derived from the reaction product of a phenol, selected fromthe group consisting of phenol, cresol, and cresylic acid, and analdehyde selected fromthe group consisting of formaldehyde andparaformaldehyde, there being admixed with the resin from 0.5% to 3% byweight of a suspending agent selected from the group consisting ofcarboxy methyl cellulose, methyl cellulose, casein, sodium alginate, andgum tragacanth, from 0.1% to 3%' by Weight of a dispersing agentselected from the group consisting of sodium and calcium ligninsulphonate, and substantially 0.2% by weight of an alkali to solubilizethe dispersing agent, there being suspended in the resin varnish atleast one mineral compound selected from the group consisting ofaluminum oxide and silicon carbide in an amount by weight, based on theweight of the emulsifiedphenolic resin varnish as follows, 5% to 30% ofaluminum oxide, 10% to 60% of silicon carbide.

7. A resinous impregnating composition comprising an A-stage emulsifiedphenolic resin comprising the potentially thermosettable reactionproduct of a phenol selected from the group consisting of phenol,cresol, and cresylic acid and an aldehyde selected from the groupconsisting of formaldehyde and paraformaldehyde, having admixedtherewith from 0.5% to 3% by Weight of a suspending agent selected fromthe group consisting of carboxy methyl cellulose, methyl cellulose,casein, sodium alginate, and gum tragacanth, from 0.1% to 3% by Weightof a dispersing agent selected from the group consisting of sodium andcalcium lignin sulphonate, and substantially 0.2% by weight of an alkalito solubilize the dispersing agent, the emulsified resin havingsuspended therein from 3% to 20% by weight of graphite, based on theweight of the emulsified resin.

8. The resinous impregnating composition of claim 7 in which there isadmixed from 5% to 25% by Weight, based on the weight of the emulsifiedresin of an alcohol selected from the group consisting of methyl, ethyl,and propyl, the alcohol acting as a stabilizing agent for the resinemulsion.

9. A resinous impregnating composition comprising an A-stage emulsifiedphenolic resin comprising the potentially thermosettable reactionproduct of a phenol selected from the group consisting of phenol,cresol, and cresylic acid and an aldehyde selected from the groupconsisting of formaldehyde and paraforrnaldehyde, having admixedtherewith from 0.5% to 3% by weight of a suspending agent selected fromthe group consisting of carboxy methyl cellulose, methyl cellulose,casein, sodium alginate, and gum tragacanth, from 0.1% to 3% by weightof a dispersing agent selected from the group consisting of sodium andcalcium lignin sulphonate, and substantially 0.2% by Weight of an alkalito solubilize the dispersing agent, the emulsified resin havingsuspended therein at least one mineral compound.

10. The resinous impregnating composition of claim 9 in which there isadmixed from 5% to 25% by weight, based on the weight of the emulsifiedresin of an alcohol selected from the group consisting of methyl, ethyl,and propyl, the alcohol acting as a stabilizing agent for the resinemulsion.

11. In a laminated article, a plurality of resin impregnated sheetsbonded together by heat and pressure as a Whole, the sheets beinginitially impregnated with an emulsified phenolic resin varnish, theresin being derived from the reaction product of a phenol, selected fromthe group consisting of phenol, cresol, and cresylic acid, and analdehyde selected from the group consisting of formaldehyde andparaformaldehyde, there being admixed with the resin from 0.5% to 3% byWeight of a suspending agent selected from the group consisting ofcarboxy methyl cellulose, methyl cellulose, casein, sodium alginate, andgum tragacanth, from 0.1% to 3% by weight of a dispersing agent selectedfrom the group consisting of sodium and calcium lignin sulphonate, andsubstantially 0.2% by Weight of an alkali to solubilize the dispersingagent, there being suspended in the resin varnish from 3% to 20% byweight of graphite, based on the weight of the emulsified resin varnish.

12. In a laminated article, a plurality of resin impregnated sheetsbonded together by heat and pressure as a whole, the sheets beinginitially impregnated with an emulsified phenolic resin varnish, theresin being derived from the reaction product of a phenol, selected fromthe group consisting of phenol, cresol, and cresylic acid, and analdehyde selected from the group consisting of formaldehyde andparaformaldehyde, there being admixed with the resin from 0.5% to 3% byweight of a suspending agent selected from the group consisting ofcarboxy methyl cellulose, methyl cellulose, casein, sodium algimate, andgum tragacanth, from 0.1% to 3% by weight of a dispersing agent selectedfrom the group consisting 8 of-sodium and calcium lignin sulphonate, andsubstantially 0.2% by weight of an alkali to solubilize the dispersingagent, there being suspended in the resin varnish at least one finelydivided mineral compound for modifying the properties of the article.

References Cited in the file of this patent UNITED STATES PATENTS1,458,943 Kinney June 19, 1923 2,061,931 Benner et al Nov. 24, 19362,190,672 Meharg Feb. 20, 1940 2,233,206 Frederick Feb. 25, 19412,385,320 Greene et al Sept. 18, 1945 2,427,481 Weible Sept. 16, 19472,433,643 Beach et a1 Dec. 30, 1947 2,462,253 Booty Feb. 22, 19492,467,498 Redfern Apr. 19, 1949 2,489,228 Rudd Nov. 22, 1949 2,525,835Schmutzler Oct. 17, 1950 2,530,770 Hopperstead Nov. 21, 1950 2,562,641Saunders July 31, 1951 2,581,301 Saywell Jan. 1, 1952 2,600,321 PyleJune 20, 1952

1. A RESINOUS IMPREGNATING COMPOSITION COMPRISING AN A-STAGE EMULSIFIEDPHENOLIC RESIN COMPRISING THE POTENTIALLY THERMOSETTABLE REACTIONPRODUCT OF A PHENOL SELECTED FROM THE GROUP CONSISTING OF PHENOL,CRESOL, AND CRESYLIC ACID AND AN ALDEHYDE SELECTED FROM THE GROUPCONSISTING OF FORMALDEHYDE AND PARAFORMALDEHYDE, HAVING ADMIXEDTHEREWITH FROM 0.5% TO 3% BY WEIGHT OF A SUSPENDING AGENT SELECTED FROMTHE GROUP CONSISTING OF CARBOXY METHYL CELLULOSE, METHYL CELLULOSE,CASEIN, SODIUM ALGINATE, AND GUM TRAGACANTH, FROM 0.1% TO 3% BY WEIGHTOF A DISPERSING AGENT SELECTED FROM THE GROUP CONSISTING OF SODIUM ANDCALCIUM LIGNIN SULPHONATE, AND SUBSTANTIALLY 0.2% BY WEIGHT OF AN ALKALITO SOLUBILIZE THE DISPERSING AGENT, THE EMULSIFIED RESIN HAVINGSUSPENDED THERE AT LEAST ONE MINERAL COMPOUND SELECTED FROM THE GROUPCONSISTING OF ALUMINUM OXIDE, AND SILICON CARBIDE IN AN AMOUNT BYWEIGHT, BASED ON THE WEIGHT OF THE EMULSIFIED RESIN, AS FOLLOWS: 5% TO30% OF ALUMINUM OXIDE, AND 10% TO 60% OF SILICON CARBIDE.
 3. A LAMINATEDMATERIAL COMPRISING, IN COMBINATION A FIBROUS BASE MATERIAL, AT LEASTONE MINERAL COMPOUND FOR MODIFYING THE PROPERITIES OF THE MATERIAL, ASMALL BUT EFFECTIVE AMOUNT OF A SUSPENDING AGENT FOR THE MINERAL METHYLCELLULOSE, METHYL CELLULOSE, CASEIN, SODIUM ALGINATE AND GUM TRAGACANTH,A SMALL BUT EFFECTIVE AMOUNT OF A DISPERSING AGENT OF A LIGNINSULPHONATE, A SMALL BUT EFFECTIVE AMOUNT OF AN ALKALI TO SOLUBILIZE THEDISPERSING AGENT, AND A PHENOLIC RESIN COMPRISING THE POTENTIALLYTHERMOSETTABLE REACTION PRODUCT OF A PHENOL SELECTED FROM THE GROUPCONSISTING OF PHENOL, CRESOL, AND CRESYLIC ACID AND AN ALDEHYDE SELECTEDFROM THE GROUP CONSISTING OF FORMALDEHYDE AND PARAFORMALDEHYDE, THEWHOLE CONSOLIDATED UNDER HEAT AND PRESSURE.